1 dead cylinder

[posnick]

Still having issues with this 98 summit 670. both cylinders is 135-140. cyclinder # 1 will not fire. I tried everything. i switched plugs and wires. i even thought it could be a carb issue so i switched the carbs around. still no luck. when the sled is running the temperature on #2 is 1100 to 1200 degrees, on cylinder #1 only 200 to 250 degrees. What could be causing it not to fire?

 

[Summiteer]

Still having issues with this 98 summit 670. both cylinders is 135-140. cyclinder # 1 will not fire. I tried everything. i switched plugs and wires. i even thought it could be a carb issue so i switched the carbs around. still no luck. when the sled is running the temperature on #2 is 1100 to 1200 degrees, on cylinder #1 only 200 to 250 degrees. What could be causing it not to fire?

Could it be the CDI?

 

[posnick]

i dont think so. if i ttake the wire from cylinder 1 and put it on 2 its still the same. I really dont want to have to take it in to riverside. Could it have something to do with the RAVE?

 

[Summiteer]

i dont think so. if i ttake the wire from cylinder 1 and put it on 2 its still the same. I really dont want to have to take it in to riverside. Could it have something to do with the RAVE?

I don't think the Exhaust valves would cause this problem, is @1 plug wet? should be if there is fuel getting to cylinder and no fire. Would an out of position rotary valve cause these symptoms?

 

[posnick]

ok. i just went and checked and #1 plug is dry. I swapped the carbs around again and re-tested. # 1 plug is still dry. Which means no fule is getting to # 1 cylinder. i baffled

 

[Summiteer]

ok. i just went and checked and #1 plug is dry. I swapped the carbs around again and re-tested. # 1 plug is still dry. Which means no fule is getting to # 1 cylinder. i baffled

10 year old fuel lines?

 

[99summitx]

Is there fuel in the main line going into the carb, could be a hole in the fuel pump diaphram or kink/blockage in line going to carb#1, it has to be between fuel pump and carb.

 

[posnick]

there seems to be fuel getting to the carb. if i disconnect the fuel line at the pet cock and disconnect it from the carbs then blow into it, fuel does come out at both carbs

 

[Summiteer]

Is this something that just happened or has the engine been opened up since it last ran properly?

 

[99summitx]

there seems to be fuel getting to the carb. if i disconnect the fuel line at the pet cock and disconnect it from the carbs then blow into it, fuel does come out at both carbs

I would check your fuel pump, I had one flooding and found a little piece of crap in pump right in front of one of the lines out so most gas was going to one side.
PUMP VERIFICATION
Check fuel pump valves operation as follows:
Connect a clean plastic tubing to the inlet nipple
and alternately apply pressure and vacuum with
pump of leak test kit. The inlet valve should release
with pressure and hold under vacuum.
Repeat the same procedure at the outlet nipple.
This time the outlet valve should hold with pressure
and release under vacuum.
NOTE: On model fitted with 2 outlets, plug 1 outlet
with finger while checking outlet valve.
Check impulse diaphragm and gasket on highsupply
fuel pump with twin outlets as follows:
Connect a clean plastic tubing to the impulse nipple
and plug vent hole on top cover. Either apply
pressure or vacuum. The diaphragm/gasket must not leak.

 

[posnick]

i just got the sled. A buddy of mine bought it 3 years ago. ran it for 1 season then parked it for the last 2 years. When i got it home pulled the carbs off and did a compression test. #1 was only 60 lbs. I asked for help on here and was told to put it back together, get it running and then retest it, so i did. The carbs have been cleaned also. the wierd thing is that everything works fine on #2 but when i put it all on #1....nuttin. plug doesnt even get wet....

 

[posnick]

i will try but... i dont know...where can i get a leak test kit? Crappy tire?

 

[posnick]

ok 99 summitx. what you are thinking is the fuel pump is pumping harder out of 1 orfice than the other, corrct? so if i was to switch the fuels lines coming out of the pump, it should create the same issue on #2 cylinder? Im trying to figure out a way to test this without buying a test kit:d which reminds me...im outta

 

[Summiteer]

ok 99 summitx. what you are thinking is the fuel pump is pumping harder out of 1 orfice than the other, corrct? so if i was to switch the fuels lines coming out of the pump, it should create the same issue on #2 cylinder? Im trying to figure out a way to test this without buying a test kit:d which reminds me...im outta

That should be the case.

 

[posnick]

after im done cooking supper and feed kids i will go try it. ( i have the lap on the counter while im cooking!) and women say men cant do 2 things at once!!! HA!!!!

 

[posnick]

no luck. i reversed the main fuel lines from carb to carb and result is the same. still no detonation in #1. even if the compression was really bad in that cylinder , it should still fire. right?

 

[posnick]

I have fuel and i have spark however there does not seem to be fuel getting into the cylinder. almost like there is not enough vacuum to suck fuel into it. Could it be that the compression reading is false ( i know its not my tester) and compression is simply too low?

 

[99summitx]

Very strange, as for the leak test you can just lightly blow and suck into the fuel pump and you will feel and hear the diaphrams moving inside. Still would not hurt to pull it out and open it up and check. The only other thing I can think is your dpm, there are 4 little hoses coming off the front of the dpm on the airbox, try moving them around, you will have to mark them to get them back right, mack sure the tube goes to correct nipple as one is vacume and one is pressure.

 

[posnick]

i dont have an air box k&n filters on this one. Lots of mods to it. Specialty sleds head in intake on it. i will test the fuel pump but im positive thats not it

 

[Summiteer]

With your carbs off, can you see the rotary valve turning and does the opening seem to cross both intake ports with the piston in the same position?
What kind of shape are your carb boots in?